"Consciousness" is the feeling that each individual has of his own existence (self-awareness) and also the state which permits him to perceive his environment (consciousness and wakefulness). These two types of consciousness, apparently quite different, are in fact the two converging stems of the perceptions that the nervous system provides to the organism. To explain this better, it is necessary to refer to the evolution of the nervous system organization among the species and to imagine what perception the nervous system provides at each stage of this evolution, or in each species harbouring a nervous system corresponding to a given stage. At the beginning, the role of the nervous system is to protect the organism and only by an automatic and reflex organization. It corresponds to an unconscious alertness which permits to perceive the environment; it is the prefiguration of the future consciousness. Self-awareness seems to appear with the centrencephalic and limbic structures which are the highest part of the nervous system in the inferior mammals and the central part in man. At this stage, acquisition memory and affectivity with its different manifestations (emotions, mood, pain...) are established. This kind of consciousness is difficult to imagine since it is only sensorial and affective. Mental consciousness appears with the mental activity in the cerebral hemispheres. It is more than likely that it exists in the superior mammals though it is impossible to imagine what it corresponds to. It reaches the highest development in the man in whose the frontal lobes have the largest extent. Speech is the most striking figure of this development. At each stage of the evolution, consciousness expresses the nervous system activity, centered on a perception, the level of which corresponds to the improvements occurring at each stage and superadded to the previous ones. Hence it is obvious that consciousness has no specific center or pathway. It relies upon structures that participate in triggering and regulating the nervous activity and that utilize the particular centers of perception and analysis. These structures are: the reticular formation and the diffuse thalamic system.(ABSTRACT TRUNCATED AT 400 WORDS)
“意识”是每个人对自身存在的感觉（自我意识），也是使他能够感知周围环境的状态（意识与清醒）。这两种意识类型，表面上截然不同，实际上却是神经系统为机体提供的感知的两个交汇源头。为了更好地解释这一点，有必要提及物种间神经系统组织的进化，并设想在这一进化的每个阶段，或者在每个拥有对应特定阶段神经系统的物种中，神经系统提供了怎样的感知。起初，神经系统的作用是通过自动和反射性组织来保护机体。它对应着一种无意识的警觉，使机体能够感知环境；这是未来意识的雏形。自我意识似乎随着中脑和边缘结构的出现而产生，这些结构在低等哺乳动物中是神经系统的最高部分，在人类中则是中枢部分。在这个阶段，习得性记忆以及带有不同表现形式（情绪、心境、疼痛等）的情感性得以确立。这种意识很难想象，因为它仅仅是感官性和情感性的。心理意识随着大脑半球的心理活动而出现。虽然无法想象它具体是什么样子，但很可能存在于高等哺乳动物中。它在人类身上发展到最高程度，人类的额叶范围最大。语言是这一发展最显著的标志。在进化的每个阶段，意识都以一种感知为中心，表达神经系统的活动，其水平与每个阶段出现的进步相对应，并叠加在先前的进步之上。因此很明显，意识没有特定的中心或通路。它依赖于参与触发和调节神经活动、利用特定感知和分析中心的结构。这些结构包括：网状结构和弥散性丘脑系统。（摘要截选至400字）
